Grammy AwardsUnderboob'BARELY' Met CBS' Standards

2/11/2013 12:38 PM PST

2013 Grammys Dress Code -- Underboob 'Barely' Met CBS' Standards

EXCLUSIVE

Katy Perry's giant TA-TA's ... Alicia Keys﻿' underboobs ... Kelly Rowland's twins ... turns out they were all given the stamp of approval from CBS -- despite the network's previously harsh warning to keep the nakedness to a minimum.

Despite these revealing outfits -- and several more -- a rep for CBS tells TMZ, "All wardrobe selections passed our standards, if only barely."

You'll remember … CBS issued a memo urging everyone in attendance to cover up or else -- saying in part: "Please be sure that buttocks and female breasts are adequately covered. Thong type costumes are problematic. Please avoid exposing bare fleshy under curves of the buttocks and buttock crack."